Superheated-liquid-droplet technique for measuring alpha decays in uranium solutions

Experimental and computational studies of the superheated-liquid-droplet (SLD) method for measuring alpha decays in uranium solutions have been conducted. The standard uranium solutions were mixed with the SLD emulsion. An alpha particle upon intersecting a liquid freon-12 droplet may evaporate the droplet, and form a bubble. The acoustic wave accompanying the bubble formation can be recorded by a piezoelectric sensor. The number of bubbles recorded represent a measurement of the alpha activity. The measured bubble nucleation rate was more than tenfolds of the theoretical estimation based on the model assuming that the uranium nuclides are homogeneously distributed through out the emulsion. To account for the dramatic difference between the measured result and the theoretical estimation, a revised theoretical model was proposed. The revised model assumes that uranium nuclides preferentially adhere to the surface of freon-12 droplets. Based on the revised model, the estimated efficiencies of detecting alpha decays increase to ∼50% which agree well with the measured results.